This invention relates to control valves, and in particular, modular control valve assemblies for vacuum and low pressure pneumatic applications.
Control valves for vacuum and low pressure applications are well known in the field of pneumatics control systems. Many types and varieties of control valves have been developed to accommodate the wide range of application requirements. Some control valves are designed to be normally open or normally closed. Other valves have multiple inlet and outlet ports and others provide three and four way valving from a single valve. Typically, control valves are actuated by their own internal control mechanisms and are operatively connected to an electrical or pneumatic line, which controls the operation of the valves.
Conventional control valves have several design limitations and cost restrictions, particularly in low pressure and vacuum applications. The valve housings are constructed of cast metals, such as brass and aluminum which makes the valves heavy and expensive. In low pressure pneumatic applications, constructing valve housings of brass and aluminum is often unnecessary for fluid control or safety purposes and simply adds cost to the system. A simple plastic valve housing often would provide sufficient structural integrity to the valve. In addition, valve housings must also be cast or machined to enclose the internal valving components and intricate flow passages. Valves traditionally have complex internal actuation components, including springs, poppets, seals, and diaphragms incorporated into sophisticated metal valve housings. The internal passages and components are even more intricate in multi-port multi-way valves. These intricate internal components are often subject to wear and contamination failure, which require maintenance in order to ensure the longevity of the valve and pneumatic system. The integration of the actuation mechanism into the valve housing often makes it more cost effective to replace the valve than to repair it.
Conventional control valves are not designed or well suited for integration into a wide range of pneumatic applications. Since plastic piping is cost effective for most pneumatic applications, conventional control valves must be connected to plastic pipe systems. Integrating conventional cast metal control valves into plastic piping systems is difficult and adds considerable fittings, supports, weight and cost to pneumatic applications. Because of the cost of cast or machined metal housings, the range of sizes of conventional control valves is often limited. The use of small control valves in many pneumatic applications creates flow restriction problems. Conventional control valves often require expensive filtration systems to reduce obstructed flow passages and prolong the life of the valves. Conventional control valves are also limited in the range of pipe fitting sizes. As a result, bushings and reducers must used to mate the control valves to larger piping systems, which adds to application costs. Furthermore, conventional control valves are also ill suited because of the type of application in which they are incorporated. For example, many pneumatic applications require the control of alternating positive and negative (vacuum) air pressures. In such applications, conventional valve designs are not well suited for dual purpose use with positive and negative pressure.
Heretofore, control valves have not been developed that employ modular design systems, so that individual valve units and valving components can be selectively combined into a complex valve assembly that allows the individual valve unit to operate from a common actuation component. While individual valves can be employed in series and parallel connected by pipe sections, to create an infinite array of pneumatic systems, each valve must be individually controlled. Electrical or pneumatic control lines must be routed to each control valve in the system, which complicates the system. Multi-port, multi-way valves (3-way valves, 4-way valves, etc. . . . ) provide greater design flexibility, but are generally more expensive and costly to maintain. A modular valve system would allow low cost individual valve units and components to be conveniently interconnected into more complex valve assemblies for integration into any particular design application. A modular valve system would also reduce the number of control lines needed to control the valve assembly in a given application thereby reducing costs.
The modular valve assembly of this invention addresses many of the traditional shortcomings of conventional control valves, particularly in vacuum and low pressure pneumatic applications. The modular valve assembly of this invention includes individual valve units and components, which can be selectively combined to form an integrated multi-port, multi-way valve assembly that is operated by a single common linear actuator. The modular design of this invention is facilitated by the construction of valve housings and valve components of the individual valve units and assemblies constructed of common plumbing pipes and fittings, such as, tee joints, threaded couplings, bushings and reducers. Common tee joints provide the basic configuration of the individual valve units. A linear actuator, such as a conventional solenoid or piston cylinder mounted to the end of the valve housing, reciprocates an elongated shaft running axially through the valve interior to move a valve disc into and out of engagement with an internal valve seat. Because the valve housings and components are constructed from common plumbing pipes and fittings, individual valve units can be connected end to end along with other valve components to form an integrated multi-port, multi-way valve assembly. The multi-way valving for such valve assembly is accomplished connecting multiple valve discs to a common valve shaft reciprocated by a single actuator to seal against multiple internal valve seats.
Accordingly, an advantage of the modular valve assembly of this invention over conventional control valves is that it allows individual valve units and components to be selectively combined and integrated into larger more complex valve assembles as required for any particular application.
Another advantage of the modular design of this valve assembly is that it allows individual valve units and components to be readily serviced and replaced with minimum labor, effort and disruption to the valve system in which it is incorporated.
Another advantage is the construction of the valve assembly from common PVC plumbing pipes and fittings, which reduces the cost, weight and complexity of the individual valve units, valve components and integrated valve assemblies.
Another advantage of this valve assembly is that use of common plumbing joints and fittings as valve housings allows the valves to be readily connected to both pipe and hose lines of vacuum and pneumatic systems.
Another advantage of this valve assembly is that it can tolerate extreme environments and be used with air flows containing high particulate counts, because the valve housings provide large open flow passages.
Another advantage is that this modular valve assembly can be scaled up and down to accommodate any application consideration.
Another advantage is that the design of this modular valve assembly reduces the cost of producing valve assembles for a wide range of pneumatic applications by eliminating the expense of tooling, castings and machining valve assembles in various configurations and scales.
Another advantage is that the design of this valve assembly provides for adjustable port orientations both radially and axially.
Other advantages will become apparent upon a reading of the following description.